Orthorhombic structure stabilazation in bulk HfO2 by yttrium doping

2021 ◽  
Vol 242 (1) ◽  
Author(s):  
D. Banerjee ◽  
C. C. Dey ◽  
R. Sewak ◽  
S. V. Thakare ◽  
D. Toprek
Keyword(s):  
Orthorhombic Structure ◽  
Yttrium Doping

scholarly journals Magnetocaloric Ln(HCO2)(C2O4) frameworks: Synthesis, Structure and Magnetic Properties

2021 ◽  
Author(s):  
Mario Falsaperna ◽  
Gavin B G Stenning ◽  
Ivan da Silva ◽  
Paul James Saines
Keyword(s):  
Magnetic Properties ◽  
Orthorhombic Structure ◽  
One Dimensional ◽  
Coordination Frameworks

This study probes the structure and the magnetic properties of members of the Ln(HCO2)(C2O4) (Ln = Sm3+-Er3+) family of coordination frameworks. These frameworks adopt a Pnma orthorhombic structure with one-dimensional...

TEM Characterization of Pseudotetragonal Mullite

2001 ◽  
Vol 7 (S2) ◽  
pp. 426-427
Author(s):  
Bradley R. Johnson ◽  
Waltraud M. Kriven
Keyword(s):  
Phase Diagram ◽  
Spatial Relationship ◽  
Equilibrium Structure ◽  
Lattice Parameters ◽  
Orthorhombic Structure ◽  
Containerless Processing ◽  
Rich Phase ◽  
Tem Characterization ◽  
Solution Field

Mullite (3Al2O3•2SiO2) exists in a solid solution field (∼57-63 mol% Al2O3) as the only stable compound in the Al2O3•SiO2 phase diagram at ambient pressures. Equilibrium 3:2 mullite has an orthorhombic structure with b>a (o-mullite). However, when initially crystallized from molecularly mixed, 3:2 precursors at temperatures < 1200°C, the first phase that forms has lattice parameters with a ≈b. This structure is often termed pseudotetragonal mullite (pt-mullite), since even when the ‘a’ and ‘b’ lattice parameters are identical, they are symmetrically independent. Pseudotetragonal mullite has been shown to contain approx. 70 mol% Al2O3. with increasing time and temperature, the structure gradually assimilates the residual SiO2, and the lattice parameters change, such that by 1400°C, the material has attained its equilibrium structure and composition.TEM was used to determine the spatial relationship between the crystalline phase and the residual, amorphous, SiO2-rich phase in pt-mullite. The starting materials were quenched, 3:2 mullite beads and fibers (made by containerless processing).

COMPOSITION DEPENDENCE OF SUPERCONDUCTIVITY AND CRYSTAL STRUCTURE IN La(Ba1−xCax)2Cu3O7−y SYSTEM

1989 ◽  
Vol 03 (04) ◽  
pp. 307-311 ◽  
Author(s):  
N. CAO ◽  
J.Q. ZHENG ◽  
X.Y. SHAO ◽  
X.S. CHEN ◽  
W.Y. GUAN
Keyword(s):  
Crystal Structure ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Composition Dependence ◽  
Superconducting Transition ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
Zero Resistance

The composition dependence of superconductivity and crystal structure in La ( Ba 1−x Ca x)2 Cu 3 O 7−y system was determined by the resistivity measurements and X-ray diffraction analysis. The superconducting transition temperature is raised with the increase of Ca content till x=0.6, at which the zero resistance temperature of the sample is 81.5 K. In the meanwhile, the crystal structure of the sample changed from tetragonal (x=0) to orthorhombic structure (x=0.2, 0.4, 0.6). With further increase of Ca content, the superconductivity decrease for the sample of x=0.8 with mixed phases including the orthorhombic oxygen-deficient perovskite-like (ODP) structure and no superconducting transition is found at 4.2 K for the sample of x=1 without the ODP structure. A possible explanation of these experimental results is given.

Colossal Magnetoresistance in Thick La0.7Ca0.3MnO3 Films

1995 ◽  
Vol 384 ◽  
Author(s):  
Randolph E. Treece ◽  
P. Dorsey ◽  
M. Rubinstein ◽  
J. M. Byers ◽  
J. S. Horwitz ◽  
...  
Keyword(s):  
Colossal Magnetoresistance ◽  
Single Phase ◽  
Laser Deposition ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
Post Deposition Annealing ◽  
X Ray ◽  
Mr Effect ◽  
Deposited Films ◽  
Post Deposition

ABSTRACTThick films (0.6 and 2.0 μm) of the colossal magnetoresistance (CMR) material, La0.7Ca0.3MnO3 (LCMO), have been grown by pulsed laser deposition (PLD). The films were grown from single-phase LCMO targets in 100 mTorr 02 pressures and the material deposited on (100) LaAlO3 substrates at deposition temperatures of 800°C. The deposited films were characterized by X-ray diffraction (XRD), magnetic field-dependent resistivity, and Rutherford backscattering spectroscopy (RBS). The LCMO films were shown by XRD to adopt an orthorhombic structure. Brief post-deposition annealing led to ~50,000% and ~12,000% MR effect in the 0.6 μm and 2.0 μm films, respectively.

Effect of Yttrium Doping on Magneto-transport Properties of Bi(Pb)-2212 Superconductors

2012 ◽  
Vol 26 (4) ◽  
pp. 913-917 ◽  
Author(s):  
Y. Boudjadja ◽  
A. Amira ◽  
A. Saoudel ◽  
L. Amirouche ◽  
N. Mahamdioua ◽  
...  
Keyword(s):  
Transport Properties ◽  
Yttrium Doping

The Synthesis of YBa3Cu4Ox Superconductor and Comparison with YBa2Cu3Ox

2014 ◽  
Vol 979 ◽  
pp. 220-223
Author(s):  
Piyamas Chainok ◽  
Supphadate Sujinnapram ◽  
Tunyanop Nilkamjon ◽  
Sermsuk Ratreng ◽  
Kiattipong Somsri ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Grain Size ◽  
Solid State ◽  
Solid State Reaction ◽  
Profile Analysis ◽  
Analysis Method ◽  
Orthorhombic Structure ◽  
Resistivity Measurements ◽  
Full Profile ◽  
Sem Micrograph

In this research, the Y123 (YBa2Cu3Ox) and Y134 (YBa3Cu4Ox) superconductors were synthesized by solid state reaction and melt process, respectively. The crystal structure of all the samples were then determined using the Rietveld full-profile analysis method to indicate orthorhombic structure. The resistivity measurements showing Tc onset of Y123 lower than Y134 for solid state reaction but higher than Y134 melt process. However, the critical temperature off-set of Y134 has lower than of Y123. The SEM and EDX show that all samples were inhomogeneous. The SEM micrograph for solid state reaction Y123 has many pores between the grain and the grain size clearly demonstrated and bigger than Y134. It was seen that these pores are party eliminated in melt process samples. FTIR spectra detected the trace of carbonate residue in all samples.

Dissolution Characteristics and Morphology of Large-sized Scorodite Particles Synthesized from Fe(II) and As(V) in Aqueous Solution

2012 ◽  
Vol 31 (4-5) ◽  
pp. 451-458 ◽  
Author(s):  
S. Fujieda ◽  
K. Shinoda ◽  
T. Inanaga ◽  
M. Abumiya ◽  
S. Suzuki
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Surface Defects ◽  
Atmospheric Temperature ◽  
Orthorhombic Structure ◽  
X Ray ◽  
Long Term Storage ◽  
Transmission Electron ◽  
Term Storage

AbstractA novel process for preparing scorodite particles with a diameter of approximately 20 µm from Fe(II) and As(V) in aqueous solution has been developed by DOWA Metals and Mining. In the present study, the dissolution characteristics of iron and arsenic from the scorodite particles synthesized by this process have been investigated under different conditions. The results show that the concentration of arsenic dissolved from the particles in aqueous solution is very low, but it has a complicated dependence on the temperature and pH of the solution. Transmission electron microscopy (TEM) with an energy dispersive X-ray spectrometer (EDS) was used to analyze the morphology, structure, and composition of the scorodite particles. The results indicate that the scorodite particles exhibit a nearly octahedral shape with planes composed of almost (111) planes in the orthorhombic structure. The concentration of iron at the surface of the particles is higher than that of iron inside of the particles. This characteristic morphology, along with the minimal surface defects of the scorodite particles, is considered to be responsible for the low dissolution of arsenic from the particles in aqueous solution. Atmospheric temperature and solution conditions were also found to be important for the safe, long-term storage of arsenic using scorodite particles.

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